The existing mobile device with a metal body can only be provided with an antenna inside, eg., the internal antenna is formed by electroplating an antenna pattern or printing conductive ink on a plastic substrate. The antenna is arranged at an upper or lower end of the mobile device, or at a broadside. In order to export a signal, upper and lower ends of back shell is assembled with glass, or the back shell is provided with a groove filled with the insulating plastic, so as to avoid the signal from being disturbed and to allow the signal to be exported. Therefore, it is impossible for a mobile device with the antenna arranged in the above described way to be of a metallic appearance as a whole. At the same time, the groove arranged therefrom not only adversely affects aesthetics, but also makes the signal intensity reduced due to partitioned metal body.